Today's strip mill lines make great demands on the construction of strip coiling machines. They must be capable of coiling material qualities up to super-strong tube steel and high-duty steels at temperatures of up to 500.degree. C approximately. Strip thicknesses of 20 to 25 mm are quite common. The widths of the strip approach roughly 2300 mm, with bundle weights being about 45 tons. If thinner strips are to be coiled, higher arrival speeds at the reel installation are necessary which may amount to 14 to 15 meters per second approximately. On the other hand, short periods are expected for the start-up of the mandrel reel, as well as for further acceleration, and also for deceleration of the mandrel with the fully coiled bundle. Furthermore, bundles must be clean and coiled with straight edges which is accomplished by securely held strip, secure tension on the strip, and good lead around the mandrel. The mandrel reel is expected to withstand high static periods at a maximum load of at least one million or more tons.
The known coiling machine connects the expanding segments with the body of the mandrel via levers, and uses a strain-stress rod to swivel all levers in and out, whereby the mandrel reel is expanded or contracted. This is to facilitate rotation of the mandrel reel with retracted expanding segments before the start of the actual reeling process to absorb the occurring centrifugal forces by way of the levers. Thus, the mandrel is no longer required to start coiling the strip in an expanded or pre-expanded condition, as was the case previously, but is expanded only after the mandrel has taken up the strip.
Today's technical standard makes great demands on the mandrel reel with respect to strip and coiling quality as well as high threading speed. In order to live up to these demands and to achieve secure strip tension the mandrel must be capable of ensuring exact slot setting of the coiling rollers by staying true to form.